There is broad national interest among commercial and public sector health care payers in new models of paying for and delivering health care services in an effort to control health care spending growth and to improve the efficiency, coordination, and quality of care. In 2009, Blue Cross Blue Shield of Massachusetts (BCBSMA) established the Alternative Quality Contract (AQC), which pays provider organizations a global payment with performance incentives in a way that resembles accountable care organization (ACO) models authorized under the Affordable Care Act. Research indicates that the AQC was associated with lower total health care spending and improved quality of care in its initial year o implementation. No information is available on how this type of model affects care for substance use disorders (SUD), defined as illicit drug and alcohol abuse and dependence, conditions plagued by system fragmentation and characterized by low rates of detection and treatment in primary care. Only a subset of AQC organizations accepted risk for SUD treatment costs, and the AQC's effects may differ based on inclusion of SUD risk in the contract. We will contrast the effects of AQC implementation for SUD with effects for nicotine dependence, a condition not subject to the same system fragmentation as SUD but which also has low rates of detection and treatment in primary care. Using BCBSMA claims and membership data for 2006-2011 to conduct difference- in-differences (DD) analyses comparing enrollees in two intervention groups - those in AQC organizations that did and did not accept SUD risk - with enrollees not participating in the AQC, we will examine the AQC's effects on: 1) use and price of SUD and nicotine dependence services; 2) spending on SUD and nicotine dependence services; and 3) HEDIS-based performance measures for SUD treatment. We will also use qualitative methods to explore perceptions about how the AQC affects use, price, spending, and quality of SUD and nicotine dependence services among administrative and clinical leadership of BCBSMA, AQC organizations, and specialty SUD treatment facilities. Only a handful of payment and delivery system models have been implemented around the country to achieve the goals of accountable care. This study can produce critical new information about whether global payment and accountable care reduce rates of SUD under- treatment, and improve the coordination and quality of SUD care without exacerbating incentives to avoid treating this population.